Interleukin I (IL-I) is a key regulatory molecule of innate immunity as well as inflammatory processes and is thought to be the major mediator stimulating bone loss in degenerative inflammatory diseases including periodontal disease. The receptor proteins for IL-I have been cloned and named IL-I type I and type II receptors (IL-IRI, IL-IRII) and IL-I receptor accessory protein (IL-IRAcP). Both IL-IRI and IL-IRAcP are required for signal transduction while IL-IRII is a decoy receptor involved in negative regulation. In addition, a host of other proteins are involved in intracellular signaling that ultimately activates various transcription factors. The aim of these studies is to better understand the signal transduction pathways of IL-I. Specific goals include the following: 1) to better understand the mechanism of JNK activation by IL-I which may involve scaffold proteins; 2) to define the receptor-ligand-receptor interactions of the trimeric extracellular complex and 3) to better un derstand protein interactions of intracelluar regions of IL-RI and IL-IRAcP. To start these experiments I have used PCR to clone several human signaling protein cDNAs from a cDNA library into expression vectors for transient transfection experiments. These proteins include IRAK, IRAK2, TRAP 6, IL-IRI, IL-IRAcP, and MyD88.. These cDNAs and various mutants derived from them are also being subcloned into GST fusion protein constructs for protein-protein interaction studies. It is hoped that better elucidation of IL-I signal transduction may lead to improve therapeutic approaches to degenerative inflammatory diseases including periodontal disease.